Drumless-type vertical water tube natural circulation boiler

ABSTRACT

A drumless-type vertical water tube natural circulation boiler, whose convective shaft is annular in horizontal cross section and disposed in the space defined externally by the internal waterwall of the boiler furnace which is annular in its horizontal cross section, the space defined by the convective shaft accommodating platforms for servicing the boiler, this being instrumental for facilitating the servicing of convection transfer surfaces, for arranging certain communication lines in the zone near to the servicing platforms and for simplifying the design of the bearing structure of the boiler.

United States Patent Inventors Anatoly Gavrilovich Serkov Parkovaya ul., 3a, kv. I5, Belgorod; Dmitry Nikitovich Grinchenko, ul., Ya, Zhizhki, 9, kv. S, Lvov; Vasily Sergeevich Moiseev, ul., Gagarina, 4, kv. 9, Belgomd; Gennady Vasilievich Maslovsky, u1., 1B Khmelnitskogo, 50, kv. 34, Belgorod; Igor Petrovich Alexeev, ul., Litvinova, '71, 1w. I3, Belgorod, all of, U.S.S.R.

Appl. No. 837,197

Filed June 27, I969 Patented July 20, I971 e DRUMLESS-TYPE VERTICAL WATER TUBE NATURAL CIRCULATION BOILER 4 Claims. 10 Drawing Figs.

US. Cl 122/235 1R,

122/510 Int. Cl F22b 21/00 Field ofSearch 122/235,

[56] References Cited UNITED STATES PATENTS 1,774,654 9/1930 Mayr 122/335 2,723,651 11/1955 Bliss 122/333 3,302,621 2/1967 Klein 122/510 Primafy Examiner- Kenneth W. Sprague A!torney-Waters, Roditi, Schwartz & Nissen ABSTRACT: A drumless-type vertical water tube natural circulation boiler, whose convective shaft is annular in horizontal cross section and disposed in the space defined externally by the internal waterwall of the boiler furnace which is annular in its horizontal cross section, the space defined by the convective shaft accommodating platforms for servicing the boiler, this being instrumental for facilitating the servicing of convection transfer surfaces, for arranging certain communication lines in the zone near to the servicing platforms and for simplifying the design of the bearing structure of the boiler.

PATENTEI] JUL20I97I 3593.690

SHEET 2 BF 5 DRUMLESS-TYPE VERTICAL WATER TUBE NATURAL CIRCULATION BOILER The present invention relates to steam boilers and more particularly to drumless-type vertical water tube natural circulation boilers.

The boiler of the present invention is capable of a most ef fective operation under pressurized conditions and in an installation open to the atmosphere.

Well known in the art are vertical water tube boilers of a box-type design with a common wall between the furnace and the convective shaft.

The wide use of diaphragm panels in such boilers has resulted in the provision of rear walls which function as partitions between the furnace and the convective shaft. Also known in the art is a steam boiler with a furnace which is annular in horizontal cross section and has an inverse travel of the flue gases. In this boiler the convective shaft is arranged in a cylindrical passage defined by the internal furnace water wall; the boiler is parallel baffled.

Designs of drumless vertical water tube natural circulation boilers are known, in which the separation of the steam-water mixture occurs not in drums, but in separately arranged vertical cyclones connected with horizontal tubes (standby accumulators or capacities) which, as a rule, are disposed in the zone of the normal level.

When manufacturing the known vertical water tube natural circulation boilers, difficulties are encountered due to the laborious character of the process and a great specific usage of metal members. A great number of various units, including those performing similar functions, results in the unit method of repairing the boilers becoming quite complicated.

When the boiler operates under pressurized conditions or in an outdoor installation, difficulties arise due to the necessity of sealing the great external surface of the boiler as well as thermally insulating servicing and repairjobs.

In drumless-type vertical water tube natural circulation boilers now available it is impossible to use horizontal tubes (standby capacities) as a bearing structure of the boiler.

It is an object of the present invention to provide a vertical water tube natural circulation boiler which will be reliable in service, will require relatively small metal usage, be easy to manufacture and whose design will enable repairs to be made by the unit method.

It is also an object of the present invention to provide a ver tical water tube natural circulation boiler intended, predominantly, to operate under pressurized conditions and in an outdoor installation, having a relatively small external surface to be sealed and requiring no expensive servicing and repair.

In accordance with these objects, the present invention contemplates a drumless-type vertical water tube natural circula tion boiler whose water-cooled furnace is annular in horizontal cross section.

According to the invention, the convective shaft of the boiler is annular in horizontal cross section and disposed in the space defined by the internal waterwall of the furnace, and mounted in the space defined by the convective shaft are platforms for the boiler servicing.

The free space along the verticalaxis of the boiler, freely accessible in the upper and bottom portions of the boiler facilitates the servicing of the convection transfer surfaces; this space can also be utilized as a site for repairjobs as well as for tracing impulse and other communication lines of the boiler.

In the preferredembodiment of the boiler, according to the invention, it is expedient to provide toroidal headers disposed horizontally one above another, the lower one serving as an accumulation stabilizing the level-of water in the boiler and being disposed in the zone of the normal level, and the upper one being a steam header, and connection tubes between said headers and between the headers and external vertical main steam separators which are extensions of main downtake tubes serving as a three-dimensional bearing structure of the boiler.

The combination of the steam-water accumulators and the bearing structure produces a decrease in the number of different-type units of the boiler, a decrease in the metal usage of the boiler, and a reduction in the manufacture and repairs.

In a boiler whose steam capacity is above 200 tons per hour, it is expedient, that the downtake tubes which simultaneously are the main support columns of the boiler, be arranged not only along the external periphery of the boiler, but also along the internal periphery thereof.

Such an arrangement of the downtalke tubes makes it possible to considerably reduce stresses in the bearing structure and to attain a more uniform distribution ofloads on the boiler foundation.

In case the boiler is provided with a high-level economizer, it is expedient, that the steam-water mixture should be supplied not to the main steam separators, but the connection tubes between the upper and lower toroidal headers (which are members of the bearing structure) be used for preliminary separation.

The preliminary separation of the steam-water mixture supplied from the high-level economizer facilitates the operating conditions of the main separators and is instrumental for reducing the diameter or number thereof.

Given hereinbelow is a description of an exemplary embodiment of the present invention, to be had in conjunction with the accompanying drawings, wherein:

FIG. I is a longitudinal sectional view of a drumless-type vertical water tube natural circulation boiler;

FIG. 2 is a top plan view of the boiler, partly in section along lines A-A, B B, and C-C in FIG. 1;

FIG. 3 is a longitudinal sectional view of a furnace accord ing to a narrowing, first embodiment;

FIG. 4 shows the same, according to a second embodiment;

FIG. 5 is a diagram ofthe circulation circuit of the boiler.

FIG. 6 shows separate component parts of the circulation circuit;

FIG. 7 is a longitudinal section of the boiler with the arrangement of an additional row of downtake tubes over the internal periphery, first version;

FIG. 8 is a section taken along VIII-VIII of FIG. 7;

FIG. 9 shows a longitudinal section of the boiler with the arrangement of an additional row of downtake tubes over the internal periphery, according to a second embodiment;

FIG. I0 is a section taken along line XX of FIG. 9.

The boiler is provided with a furnace 1 (FIGS. 1 and 2) which is annular in horizontal cross section.

The walls of the furnace comprise an external waterwall 2 and an internal waterwall 3 (all-welded structures) that constitute upllow circulation circuits with. lower headers 4 and upper headers 5.

Some of the tubes of the external waterwall 2 at the bottom of the boiler are drawn apart to provide for a tangential arrangement of combustion devices 6.

To improve the aerodynamic characteristics depending on the type of fuel employed, a portion of the furnace may be made with a narrowing section (FIGS. 3 and 4).

In the upper portion of the internal waterwall, a furnace outlet screen 7 is provided (FIG. 1). Behind the internal waterwall a convective shaft 8 is disposed (FIGS. 1 and 2) which is annular in horizontal cross section. The shaft is sym metrical and divided by partitions 9 (FIG. 2) into sections or compartments. Disposed in the compartments are banks of heat recovery surfaces ofa steam superheater 10 (FIGS. 1, 2), of an air heater 11 (FIG. I) and of an economizer 12.

In the space defined by internal walls 13 of the shaft 8 platforms 14 are arranged for servicing the heating surfaces, the platforms being interconnected by ladders. A freight-and-passenger lift may also be provided.

The main bearing members of the boiler structure are downtake tubes 15 (FIGS. 1, 2, 5, 7-10) -450 mm. in diameter, which in the upper portion pass into main steam separators I6.

A powerful downtake system and a symmetrical design of the combustion chamber ensure reliable operation of the boiler within a wide range of loads under natural circulation conditions.

Downtake tubes 15 are interconnected by means of transverse tubes 17 (FIGS. 1, 2), and the main separators l6, are interconnected by tubes 18 which serve as additional accumulators for water.

The steam space of the main separators l6 communicates with an upper horizontally arranged header l9 via tubes 20. Under the upper toroidal header a toroidal header 2] is disposed, connected with the former by means of vertical tubes 22. Extending radially from the header 2] are tubes 23 that connect the downtake tubes 15 with said header.

The header 21 (FIG. and the tubes 23 make up an accumulator serving to stabilize the level of water in the boiler. In addition, for the same purpose, the tubes 23 are in steam and water communication with the steam and water spaces of the main separators 16 by means of small diameter tubes 24 (FIG. 6).

The tubes 22 (FIG. 5) may be made as vertical separators adapted to separate the steam and water mixture from the waterwalls 2 and 3 or from the economizer 12 (FIG. 1).

The headers 19 and 21 (FIG. 5), main separators l6 and tubes 18, 20, 22 and 23 make up a bearing floor structure, from which the waterwalls 2 and 3 are suspended.

According to the invention, in connection with the high output capacity of the boiler, its horizontal dimensions and, hence, those of the floor are increased. This fact may involve difficulties when making the floor of sufficiently great size. In such cases it is preferable to make the floors by arranging an additional row of downtake tubes a (FIGS. 7-10) along the internal periphery of the boiler. Shown in FIGS. 9 and 10 is a floor which is preferable in case the boiler structure is subject to considerable temperature expansions. The downtake tubes are combined into banks that are interconnected by bent tubes 25 which serve to compensate for relative temperature displacements of the bank.

From the furnace chamber 1 (FIG. 1), the combustion products, upon passing through the furnace outlet screen, turn through 180 and enter into the convective shaft 8, where the heat recovery surfaces are disposed. In the bottom portion of the convective shaft, hoppers 26 are arranged, where the stream of gases makes a turn and is directed into a chimney stack.

For cleaning the heat recovery surfaces from ash deposits, a shot feeder 27 is provided in the upper portion of the boiler; the shot passed through the banks of the heat recovery surfaces is collected in the hoppers 26.

The entire boiler is composed of similar sections arranged symmetrically about its vertical axis.

Each section is equipped with a multiple number of burners and comprises an internal and an external waterwall and systems of downtake tubes that constitute an individual circulation circuit of the section, and also banks of heat recovery surfaces.

If in the boiler of the invention, multistage evaporation is employed by dividing the boiler sections into condensate water evaporation and feed water evaporation sections, water from the economizer is directed into the downtake tubes of the condensate water evaporation sections only, and the feed water evaporation sections are fed by a continuous blowing over the feed water residue from the preceding sections.

The boiler can operate both under pressurized conditions and in an open installation.

If necessary, a light roofing of a tent type may be suspended from the downtake tubes and disposed over the external periphery of the boiler.

We claim:

1. A drumless-type vertical water tube natural circulation boiler, comprising: a water-cooled furnace having an annular horizontal cross section and including internal and external water-cooled walls; a convective shaft having an annular horizontal cross section and disposed within said internal water-cooled wall of the furnace; a steam header at the top of said furnace for steam accumulation; downtake tubes arranged along the external periphery of the boiler and connected with said header; and platforms for servicing said boiler arranged within the space defined by said convective shaft.

2. A boiler as claimed in claim 1 further comprising toroidal headers arranged horizontally one above the other, the lower of said headers serving as an accumulator to stabilize the level of water in the boiler, upper header constituting said steam header, external vertical main steam separators in continuation of said downtake tubes at the upper ends thereof, and a plurality of further tubes connecting the headers with each other and with said main steam separators to constitute a bearing structure for the boiler.

3. A boiler as claimed in claim 1, comprising an additional row of downtake tubes arranged along the internal periphery of the boiler, and a plurality of tubes connecting said additional downtake tubes with the first-mentioned downtake tubes, the latter tubes being disposed horizontally and constituting a bearing structure for the boiler with said downtake tubes.

4. A boiler as claimed in claim 2, wherein said tubes connecting the headers are constituted as steam preseparators fed with a steamwater mixture from a high-level economizer. 

1. A drumless-type vertical water tube natural circulation boiler, comprising: a water-cooled furnace having an annular horizontal cross section and including internal and external water-cooled walls; a convective shaft having an annular horizontal cross section and disposed within said internal watercooled wall of the furnace; a steam header at the top of said furnace for steam accumulation; downtake tubes arranged along the external periphery of the boiler and connected with said header; and platforms for servicing said boiler arranged within the space defined by said convective shaft.
 2. A boiler as claimed in claim 1 further comprising toroidal headers arranged horizontally one above the other, the lower of said headers serving as an accumulator to stabilize the level of water in the boiler, upper header constituting said steam header, external vertical main steam separators in continuation of said downtake tubes at the upper ends thereof, and a plurality of further tubes connecting the headers with each other and with said main steam separators to constitute a bearing structure for the boiler.
 3. A boiler as claimed in claim 1, comprising an additional row of downtake tubes arranged along the internal periphery of the boiler, and a plurality of tubes connecting said additional downtake tubes with the first-mentioned downtake tubes, the latter tubes being disposed horizontally and constituting a bearing structure for the boiler with said downtake tubes.
 4. A boiler as claimed in claim 2, wherein said tubes connecting the headers are constituted as steam preseparators fed with a steam-water mixture from a high-level economizer. 